The use of marking guns is well known. In the past, marking guns have commonly been used by veterinarians or wildlife management personnel to mark animals as a means of counting the wild animals, herding the wild animals, or other similar desired procedures. Another example of the use of marking guns is the marking of trees in forestry projects.
Marking guns commonly use compressed gas pressure to fire a hollow projectile generally configured as a sphere, or ball constructed of a thin wall formed of plastic or gelatin which will break upon impact with a target. Contained inside the sphere is a colored liquid such as paint.
More recently, marking guns have been used in mock "war games" or survival games. Groups or teams are formed to compete with each other as though in a "war", usually within a limited geographical area such as a woods. When members of opposing groups or teams come upon each other they use the marking guns to try to score a hit by marking the opposing member or members with the paint balls impacting on their clothing. If a member is "hit" as signified by a paint spot, that member is eliminated from the game. The group or team that has the last surviving member wins the game.